Fluctuations in the proportion of the population in an age group appear to be associated with economic, demographic and social changes with implications for mental health. The proposed research will quantify the impact of changes in the size of age groups (generational crowding and thinning) on a number of important indicators. The first part of the analysis will examine one way in which fluctuations in these variables may be generated by changes in the age distribution of the population. The second part will estimate effects of changing population proportions on labor market variables. Attention will focus on the determination of relative income levels at different ages generally, on the incomes of blacks relative to whites, on youth unemployment and on the employment of older men. Part 3 will analyze the effects of "generational crowding and thinning" on fertility, migration, suicide and crime. Models and techniques for exploring each of the components are developed drawing heavily on existing analytic methods which have not yet been applied to this problem. The extent to which the passing of the youth bulge in the age distribution will alleviate problems among youth and intensify problems at older ages will be considered along with other implications.